set default compilation

[sgrava]

Change default compilation strategy to just perform unit conversion.

The current default MAX_ENERGY profile should be set explicitly as

program.compile_to(device=..., profile="max_energy")

or as

from qoolqit.execution import CompilerProfile
program.compile_to(device=..., profile=CompilerProfile.MAX_ENERGY)

To do

• Allow string aliases in CompilerProfile
• Set compilation profile explicitly in tests and notebooks
• Set new default compilation DEFAULT. Former WORKING_POINT to deprecate.
• update documentation to reflect the new default